Due to the increasing use of small-scale optical devices such as diode lasers, optical fibers and CCD pixel elements, optics on a micron scale has become increasingly more important in science and industry. Numerous techniques have been employed to fabricate small-scale optical elements, almost all of which involve complex patterning steps followed by etching or ablation.
So called microlenses, just as their larger counterparts, can be classified as being refractive or diffractive. Examples of the latter include Fresnel zone plates which are comprised of a series of concentric light-blocking rings separated by slits. Binary optics is one technology that is suitable for fabricating Fresnel zone plate analogs and other diffractive optical elements using techniques that were originally developed for fabricating integrated circuits (i.e., photolithographic techniques). Reference in this regard can be made to the article "Binary Optics" by W. B. Veldkamp et al., Scientific American, May 1992, pps. 92-97.
In the LEOS '94 Conference Proceedings, Vol. 1, 1994, there are described several approaches to the fabrication of micro-optical components, in particular microlenses and arrays of same. In particular, reference can be had to the following four articles: W. R. Cox et al., "Microjet Fabrication of Micro-optical Components", pp. 52-53; Z. L. Liau et al., "Mass-Transport Efficient Microlenses in GaAs and GAP for Integration with High Power Diode Lasers", pp. 67-68; B. F. Aull et al., "Application of Smart-Pixel and Microlens Arrays to Early Vision", pp.149-150; and S. S. Lee et al., "An 8.times.1 Micromachined Micro-Fresnel Lens Array for Free-Space Optical Interconnect", pp.242-243.
In general, these and other known types of approaches rely on complicated multi-step processes such as surface micromachining or photolithography and etching to fabricate microlenses and microlens arrays. However, the fabrication of refractive-type microlenses is not readily accomplished by photolithographic techniques.
In U.S. Pat. Nos. 5,053,171 and 4,842,782 Portney et al. disclose the fabrication of an ophthalmic lens with an excimer laser. In this approach the laser is used ablate a surface of a plastic or glass blank.